"Escalating fare initiatives between two hub carriers has historically not been a good thing for the participating airlines' bottom lines, and by extension, their share prices," wrote Merrill analyst Michael Linenberg.

Shares of AMR Corp.
AMR, -1.86%
the parent of American Airlines, and Northwest Airlines
NWAC
were also heavily traded. AMR fell 12 cents to $17 as the most active stock, while Northwest lost 38 cents to $12.98.

JetBlue Airways
JBLU, -1.90%
fell 29 cents to $26.34. JetBlue will turn its quarterly results on Thursday and analysts forecast a per-share profit of 17 cents, according to an average estimate compiled by Thomson First Call.

Winter weather disrupted operations at major airports on Monday. Atlanta's Hartsfield International Airport, Philadelphia International Airport, Chicago's O'Hare International and Minneapolis-St. Paul International experienced weather-related flight delays from snow or poor visibility, according to the FAA's Web site.

Intraday Data provided by SIX Financial Information and subject to terms of use. Historical and current end-of-day data provided by SIX Financial Information. All quotes are in local exchange time. Real-time last sale data for U.S. stock quotes reflect trades reported through Nasdaq only. Intraday data delayed at least 15 minutes or per exchange requirements.